Train detecting apparatus



Aug. 1, 1961 H. G. wxTMER Erm. 2,994,754

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United States Patent O 2,994,764 TRAIN DETECTING APPARATUS Harold G. Witmer, Edgewood, and Lawrence R. Golladay, Forest Hills, Pa., assignors to Westinghouse Air Brake Company, Wilmerding, Pa., a corporation f Pennsylvania Filed Dec. 4, 1957, Ser. No. 700,665 9 Claims. (Cl. 246-28) Our invention relates to train detecting apparatus of the type using a stationary wayside coil in which energy is induced by a train carried permanent magnet moving past said coil in relatively close proximity thereto. More particularly our invention relates to an arrangement for checking the integrity of certain parts of the -apparatus so lthat failure of these parts will result in a fail-safe condition.

In railway signaling or traiiic control systems it is sometimes impractical or impossible to provide track circuits for the detection of track occupancy by a train. Such a problem may exist, for example, in localities where poor track shunting conditions are encountered, steel ties are used, or the provision of track circuits is economically unjustiable. Under these conditions it is often the practice to install train detecting apparatus such as magnetic detectors, light responsive apparatus, mechanical treadles, or inductors, etc. to detect the passage of a train and operate a circuit arrangement often referred to in the railway signaling art `as a trap circuit. In such a circuit arrangement, a relay is released when a train passes a rst location in a track stretch, such as a signal location, and the relay remains in the released position until the train passes a second location in said track stretch, such as another signal location. The signals `are controlled by contacts of the relay associated with the track section in advance of each respective signal. By this arrangement a train may be said to check in and check ou of a section of railway track.

One object of our invention is to provide in a checkout system using train detecting apparatus of the induction type in which an electronic switching device such as an electronic tube or transistor is triggered -by the passage of a train to momentarily energize a relay, an arrangement whereby the integrity of said electronic device and associated circuitry is checked.

Another object of our invention is to prevent, in a trap circuit arrangement, a check-out of a train from occurring if said electronic device `or associated circuitry fails either temporarily or for a long period of time.

A third object of our invention is to enforce -a manual operation, after such a failure as described above, before the `trap circuit arrangement can be restored to its normal condition.

Other objects and characteristic features of our invention will become apparent `as the description proceeds.

In practicing our invention, we Iaccomplish the foregoing objects by the use of a slow-release stick relay which repeats a back contact ofthe relay used to detect the passage of a train. A manually operated circuit controller or push button is used to pick up the slow-release relay in the event of its release, as described hereinafter.

We shall describe one arrangement of apparatus embodying our invention, and shall then point out the novel features thereof in claims.

The accompanying drawing -is a diagrammatic view showing one form of `apparatus embodying our invention.

Referring to the drawing, the train detecting apparatus here illustrated is a very simplified form of trap circuit or check-in, check-out signaling arrangement. A section of railway track T over which trains move from west to east or from left to right, as indicated by the arrow, extends ice? between two signal locations 1S and 2S. Wayside devices or inductors C1 and C2 are located at the signal locations 1S and 2S, respectively. These devices consist of a winding or coil on a magnetizable core, and are the train detecting devices.

yAll trains moving over the section are provided, preferably on the rear end thereof, with `a permanent magnet, designated M, and noted `on the drawing as a train carried magnet. The poles of the permanent magnet are not designated at it is immaterial tothe operation of `the apparatus in which vdirection the magnet moves past the wayside detecting devices Cl and C2. It is to be understood, however, that the wayside coils and the train carried magnets are to be so arranged that the magnets will move past the coils in relatively close proximity thereto as the trains pass each signal location.

Energy for the operation of the apparatus at each signal location is furnished by a suitable source of direct current such as a battery of proper voltage and current. These sources are shown on the drawings in the conventional manner as batteries and their positive and negative lterminals are identiiied by the reference characters B and N, respectively. lt is to be noted that the negative terminals of the batteries at all signal locations are connected to each other by a line conductor so that the negative poles of all the batteries are common to each other. This arrangement is necessary for continuity `of the circuits as will become apparent hereinafter in this descriptlon.

The apparatus provided at signal locations 1S and 2S is separated on the drawing by a dot-dash line extending down the middle of the drawing. Dotted lines at the lett and right hand edges of the drawing denote line conductors to the next signal locations to the rear `of signal 1S and in advance of signal 2S, respectively. Legends on the drawing indicate the apparatus to which the lines connect at said signal locations.

Detector relays designated DRI and DRZ are provided at the locations of signals 1S and 2S, respectively. The negative terminals of the windings of these relays are connected to the battery terminal N and the positive terminals of the windings are shown connected to the collectors of P-N-P type switching transistors designated D1 and D2 at signal locations 1S and 2S, respectively. While the electronic switching devices are here shown as P-N-P type transistors, it is to be understood that N-P-N type transistors or electron tubes can be used for these devices.

The bases of the transistors D1 and D2 are shown connected to one terminal of their associated wayside coils C1 and C2, respectively, and the emitters of the transistors are shown connected to the other terminal of their associated wayside coils. The emitters are also shown connected to the positive terminal of the battery at their respective location.

The values of the wayside coils and electronic switching devices are so selected that under normal conditions the devices are non-conducting and the detector relays occupy their released position. When, however, a train carrying a magnet M passes one of the wayside coils so that the field of the magnet is cut by the core of the coil, energy is induced in the coil, which energy triggers the associated electronic switching device rendering it conducting and causing the associated detector relay to be momentarily picked up. Such triggering arrangements using transistors or electron tubes are well known in the electrical art.

The means for the check-in of a train at each signal location form no part of our invention and, are shown at signal locations 1S and 2S as front contacts a of relays CHRI and CHR2, respectively. These relays are noted on the drawings as being momentarily deeper-giu@ by check-in means and may, for example, be controlled in a manner identical to that shown for relay R in Letters Patent of the United States No. 1,834,077, issued December 1, 1931, to A. I. Sorenson 'for Highway Crossing Signal. These controls are shown schematically in the drawing by the dotted lines extending `from the rails adjacent the signal locations 1S and 2S to the windings of the relays CHRI and CHRZ, respectively.

Detector relays DRI and DR2 are provided with normally picked-up slow-release back contact repeater stick relays DRP1 and DRPZ, respectively. Relay DRP1 is normally maintained picked up by a circuit which may be traced from battery terminal B through back contact aV of relay DRI, winding of relay DRP1, and front contact a of relay DRP1 to battery terminal N. Relay DRP1 is also provided With a pick-up circuit which may be traced from battery terminal B through back contact a of relay DRI, winding of relay DRP1 and a normally open contact of a manually operated spring return push button PBI, to battery terminal N. The circuits for relay DRPZ at signal 2S are similar to those just traced for relay DRP1, and it is therefore believed to be unnecessary to trace these circuits in detail. It is apparent that, if relay DRP1 or DRPZ is released, they can be picked up again only by operation of its associated manually operated push button PBI or PBZ, respectively.

Signal control or trap stick relays HRI and HRZ are shown at signal locations IS and 2S, respectively. These relaysv normally occupy a picked-up position and are maintained in that position by a stick circuit over one of their own front contacts. The stick circuit for relay HRI maybe traced from Vbattery terminal B through -front contact a of check-in relay CHRI, front contact a of relay HRI and the winding of relay HRI to battery terminal N. Relay HRI is also provided with a pick-up circuit which may be traced from battery terminal B at signal ZS throughfront Acontact a of relay DR2, front contact b of relay DRPZ, wire 20, and winding of relay HRI to battery terminal N at signal 1S location. The battery terminals N at each location being connected to each other by line conductor 21, as heretofore pointed out, a circuit may thus be completed for picking up relay HRI. The circuits for control of relay HRZ are similar to those just traced for relay HRI, and it is believed to be sucient for an understanding of these circuits to merely point out that the pick-up circuit for relay HR2 originates at the next signal location in advance of signal 2S location, as is believed apparent from the notation on the drawings.

It should be pointed out that the apparatus and circuit arrangement at all the signal locations in a stretch of railway track are similar and, therefore, it is only necessary to show two signal locations for a clear understanding of the operation of the apparatus and associated circuitry for an entire signal system.

Signals 1S and 2S may be of any of the well known types but as here shown are of the color-light type. These signals each have two lamps, green and red, designated by the reference characters GE and RE, respectively, prefixed by the number of the signal with which the lamps are associated. The indications resulting from the green or red lamps being illuminated individually are proceed and stop, respectively.

The signal control or trap relays HRI and HRZ control theindications of the associated signal YIS or 2S. The circuit for illumination of the green signal lamp IGE of signal/IS may be traced from battery terminal B through front contact b of relay HRI and the lilament of the lamp to battery terminal N. The circuit vfor illumination of the red signal lamp IRE may be traced from battery terminal B through back contact b of relay HRI and the iiiament of the lamp to battery terminal N. The circuits for the illumination of the signal lamps 2GB and ZRE of signal 2S vmay be similarly traced through contact b of relay HRZ.

The apparatus is shown in the drawings in the positions it occupies under normal conditions, that is when there are no trains in the track section T. The operation of the apparatus being similar at each signal location we will describe only the operation of the apparatus as a train checks in and checks out of track section T.

When the train shown on the drawing approaching signal IS, moves past signal 1S, relay CHRI is momentarily released, opening the stick circuit to relay HRI and releasing this latter relay. The release of relay HRI opens at front contact b the previously traced circuit for green signal lamp 1GB and closes at back contact b the circuit for red signal lamp IRE. Signal 1S is thus caused to give its stop indication when the train passes the signal. (The movement of the train past signal IS also momentarily picks up relay DRI to restore the HR relay at the next signal location to the rear, but similar operation will be described hereinafter for signal IS when the train moves past signal 2S.)

As the train moves over track section T, relay HRI remains in its released position and signal 1S will indicate stop until the train vacates the track section. When the train moves past signal 2S the train carried magnet induces energy in wayside coil C2 which triggers the elec tronic device D2 and momentarily picks up relay DR2 to complete the previously traced pick-up circuit for relay HRI over front contact a of relay DR2. Relay HRI picks up and again completes its stick circuit over its own front contact a and is thus maintained picked up. Signal IS again gives its green indication, track section T being vacated by the train. (Relay CHRZ checks the train into the track section in advance of signal 2S and controls that signal to ygive its red indication in the same manner that signal IS was controlled.)

From the above description it is apparent that we have shown a very simple form of trap circuit or check-in, check-out signaling arrangement in order to described the operation of the apparatus comprising our invention. In actual check-in, check-out signaling systems, the ararrangement would probably be much more involved, but the arrangement shown suices for a description of the operation of the apparatus of our invention.

As previously set forth relays DRPI and DRPZ are slow-release relays and their release time is suiciently long to span the momentary opening of back contacts a of relays DRI and DR2, respectively. Under ordinary operation, therefore, these slow release relays will remain picked up during the momentary picking up of relays DRI and DR2. However, if, for example, electronic device D2 becomes short-circuited so that relay DR2 remains up for a longer period of time than under ordinary operating conditions, relay DRP2 will release and open the pick-up circuit to relay HRI. The release of relay DRPZ will also open its own stick circuit through its own front contact a, and relay DRPZ will remain released until the push button PBZ is operated to again pick up the relay. It is thus apparent that if DR2 should fail to operate properly due to its associated electronic device being short-circuited either temporarily or permanentlyor ydue to some other fault in the operating circuits for relay DR2, a train which is already checked into track section T or checks into the section thereafter will not check out of the section. Under these circumstances signal IS will continue to give a stop indication and a fail-safe condition will result.

If provision is not made for checking the operation of the check-out apparatus, it is conceivable, for example, that an electronic device such as D2 may become shortcircuited and relay DR2 will pick up and subsequently remain picked up. Under these circumstances a train moving past signal IS would not deencrgize the trap relay HRI, as the pickaup circuit for that relay is steadily closed at front Contact a of relay DR2 (front contact b of relay DRPZ not being included in the circuit). The danger of such operation of the apparatus is readily apparent.

From this description it is apparent that with the apparatus of our invention as shown in the drawing, a trap circuit or check-in, check-out signaling system is provided wherein the check-out arrangement is based on the fail-safe principle. It is also apparent that a system is provided whereby either a temporary or permanent faliure of the check-out apparatus is detected and a distinct manual operation, that is, operation of a manually operated push button, is required before the apparatus can be restored to its normal condition, once it has failed.

Although we have herein shown and described only one form of apparatus embodying our invention, it will be understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of our invention.

Having thus described our invention, what we claim is:

1. In a trac control system for a section of railway track including a traic controlling device for governing the movement of trains over said track section, said device being located at a first end of said section; a normally picked-up trap stick relay at said rst end of said section, a control circuit for said trattic controlling device including a contact of said trap stick relay, and means for releasing said trap stick relay when a train passes said rst end of said track section; the combination of an electronic device located at the second end of said track section, a normally released detector relay, means operated by a train passing said second end of said track section for triggering said electronic device to cause a pulse of energy to be momentarily supplied to said detector relay, a slow-release relay at said second end of said track section, a stick circuit for said slow-release relay including a back contact of said detector relay and a front contact of said slow-release relay, a manually operable circuit controller, a pickup circuit for said slow-release relay including a normally open contact of said manually operable circuit controller, and a pickup circuit for said trap stick relay including front contacts of said detector relay and said slow-release relay.

2. In ya trap circuit arrangement for a railway traffic controlling system for a section of railway track, said arrangement including a trap stick relay which is released when a train enters said track section and a traiiic controlling device at said entrance end of said track section, said device being controlled by a circuit through a contact of said trap stick relay; in combination; a wayside coil at the exit end of said track section, said coil being so located as to be in inductive relationship with a magnet carried by said train when said train passes said coil; an electronic device connected to the terminals of said coil and to one terminal of a source of energy, a detector relay connected to said electronic device and the other terminal of said source of energy, a slow-release relay, a circuit including a back contact of said detector relay and a front contact of said slow-release relay for maintaining said slow-release relay normally picked-up, a manually operable circuit controller, a pickup circuit for said slow-release relay including a normally open contact of said manually operable circuit controller, and a pickup circuit for said trap stick relay including front contacts of said detector relay and said slow-release relay.

3. In a check-in, check-out traiiic controlling system for a section of railway track in which a stick relay is released when a train enters the track section and including a traiiic controlling device controlled by -a contact of said stick relay, in combination, a wayside coil at the exit end of said track section and arranged in the trackway so as to be in an inductive relationship with a magnet carried by a train passing the exit end of the track section; a P-N-P type of transistor, the base of which is connected to one terminal of said wayside coil and the emitter of which is connected to the other terminal of said coil and the positive terminal of a source of energy; a detector relay, one control terminal of which is connected to the collector of said transistor and the other control terminal of which is connected -to the negative terminal of said source of energy; a slow-release relay at the exit end of said track section, said relay being norm-ally maintained in a picked-up position by a circuit through a back contact of said detector relay and a front contact of said slow-release relay; a manually operable circuit controller; a pickup circuit for said slow-release relay, said circuit including a normally open contact of said circuit controller; and a pickup circuit for said first mentioned stick relay, said circuit including front contacts of said detector relay and said slow-release relay.

4. In a check-in, check-out traflic controlling system for a section of railway track in which a tratiic controlling device is controlled by a stick relay which is released when a train enters the track section; in combination, a check-out system for said track section, said system comprising, a normally non-conducting electronic device, means for actuating said device to momentarily conduct a pulse of energy when a train passes the exit end of said track section, a detector relay connected to said electronic device so as to momentarily pickup when the electronic device conducts a pulse of energy; means for checking when said electronic device is short circuited, said means including a slow-release relay ncrmally maintained picked-up by a circuit including a back contact of said detector relay and a front contact of said slow-release relay and having a pickup circuit including a normally open contact of a circuit controller; and a circuit including front contacts of said detector relay and said slow-release relay for picking up said first mentioned stick relay.

5. In combination, a section of railway track, a normally nonconducting electronic device, means responsive vto the passage of a train by `a predetermined point in said track section for momentarily biasing said device to conduct a pulse of energy, a first relay connected to be energized by said pulse of energy, a slow release relay, a manually operable circuit controller, means controlled by said circuit controller and said iirst relay for picking up said slow release relay only when said circuit controller is operated and said rst relay is released, and means controlled by said iirst relay for maintaining said slow release relay picked up when once picked up and said iirst relay remains released or is picked up and released within the release period of the slow release relay.

6. In combination, a section of railway track, a wayside coil disposed in the trackway of said section, means responsive to the passage of train-carried apparatus for inducing energy in said coil, a normally nonconducting electronic device, means including said induced energy for momentarily biasing said device to conduct a pulse of energy, a first relay connected to be energized by said pulse of energy, a slow release relay, a manually operable circuit controller having a normally open contact, a pickup circuit for said slow release relay including said contact of said circuit controller and a back contact of said rst relay, and a stick circuit for said slow release relay including one of its own front contacts and said back contact of said first relay.

7. In combination, a section of railway track, a magnet carried by each train traversing said section, a wayside coil so disposed in the trackway of said section as to be in inductive relationship with the magnet of each train passing said coil, a P-N-P type of transistor, a source of energy, a circuit connecting one terminal of said coil and the emitter of said transistor to the positive terminal of said source of energy, a circuit connecting the other terminal of said coil to the base of said transistor, a irst relay, a circuit connecting the collector of said transistor to the negative of said source of current through the winding of said relay, a slow release relay, a manually operable circuit controller having a normally open contact, a pickup circuit for said slow release relay including said contact of said controller 7 and a back contact of said first relay, and a holding circuit for said slow release relay including one of its own front contacts and said back contact of said first relay.

8. In a control arrangement for a trap stick relay in a railway trac control system for a section of railway track including means for deenergizing said trap stick relay when trains enter said track section, the combination comprising, a coil in the trackway of said section cooperating with a magnet on each train traversing said section for inducing a pulse of current in said coil, a normally nonconducting transistor, means including said induced pulse of current for momentarily biasing said transistor to conduct a pulse of energy, a first relay connected to be energized by said pulse of energy, a slow release relay normally energized by a stick circuit including a back contact of said rst relay, means controlled by said first relay for deenergizing said slow release relay when said first relay is energized for a period of time greater than the release time of the slow release relay, and means controlled by said iirst relay and said slow release relay for energizing said trap stick relay when the rst relay and the slow release relay are energized.

9. In a control arrangement for a trap stick relay in a railway traffic control system for a section of railway track including means for deenergizing said trap stick relay when a train enters said track section, the combination comprising, a coil in the trackway of said section cooperating with magnets on trains traversing said section for inducing a pulse of current in said coil, a normally nonconducting transistor, means including said coil for supplying each said pulse of current to said transistor to thereby trigger said transistor to momentarily conduct energy, a first relay connected to be energized by said energy, a slow release relay, a manually operable circuit controller, means `controlled by said circuit controller and said first relay for energizing said slow release relay when said circuit controller is operated and said first relay is released, means controlled by said first relay for maintaining said slow release relay energized when once energized and said first relay is released, means controlled by said first relay for deenergizing said slow release relay when said first relay is energized for a period of time greater than the slow release period of the slow release relay, and means controlled by said first relay and said slow release relay for energizing said trap stick relay when the first and the slow release relays are energized.

References Cited in the file of this patent UNITED STATES PATENTS 1,830,775 Wallace Nov. 10, 1931 2,030,924 Kemmerer Feb. 18, 1936 2,096,404 OHagan Oct. 19, 1937 2,183,162 Culbertson Dec. 12, 1939 2,465,794 Fereday Mar. 29, 1949 2,550,860 Preston May 1, 1951 

